In each manufacturing process of various kinds of technical fields such as a semiconductor wafer manufacturing technique, a liquid crystal display manufacturing technique, a magnetic disk manufacturing technique, and a multilayer printed circuit board manufacturing technique, there has been used a chemical liquid such as a photoresist liquid, spin-on glass liquid, polyimide resin liquid, purified water, developer, etchant, cleaning liquid, or organic solvent, and a chemical liquid supply apparatus is used for coating such chemical liquid. For example, as such, a chemical liquid supply apparatus disclosed in U.S. Pat. No. 5,061,156 has been already developed.
For example, in the case of coating the photoresist liquid to the surface of the semiconductor wafer, while the semiconductor wafer is rotated in a horizontal plane, the photoresist liquid is dropped on the surface of the semiconductor wafer from a dispensing nozzle. In such a chemical liquid supply apparatus, a filter is provided to remove foreign matters contained in the photoresist liquid.
If bubbles are mixed in the apparatus in dispensing the chemical liquid such as a photoresist liquid, the bubbles absorb pressure extruding the chemical liquid and the dispense amount of the chemical liquid becomes unsteady, whereby dispense accuracy thereof is reduced. Therefore, the removal of the bubbles is required to manufacture, with high quality and good yield, integrated circuits formed on the semiconductor wafer.
In the case of a chemical liquid supply apparatus dispensing the chemical liquid by discharge pressure of a pump therein, the bubbles collected in pump volume are ordinarily exhausted to the outside of the chemical liquid supply apparatus, by opening a deaeration valve which is attached to an exhaust flow path connected to a vent port of the filter. In such a manner, the bubbles collected in the filter can be removed to a certain degree.